package gov.nist.javax.sip.parser.ims;
/*
* Conditions Of Use 
* 
* This software was developed by employees of the National Institute of
* Standards and Technology (NIST), an agency of the Federal Government.
* Pursuant to title 15 Untied States Code Section 105, works of NIST
* employees are not subject to copyright protection in the United States
* and are considered to be in the public domain.  As a result, a formal
* license is not needed to use the software.
* 
* This software is provided by NIST as a service and is expressly
* provided "AS IS."  NIST MAKES NO WARRANTY OF ANY KIND, EXPRESS, IMPLIED
* OR STATUTORY, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTY OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT
* AND DATA ACCURACY.  NIST does not warrant or make any representations
* regarding the use of the software or the results thereof, including but
* not limited to the correctness, accuracy, reliability or usefulness of
* the software.
* 
* Permission to use this software is contingent upon your acceptance
* of the terms of this agreement
*  
* .
* 
*/
import java.text.ParseException;

import javax.sip.InvalidArgumentException;

import gov.nist.javax.sip.header.SIPHeader;
import gov.nist.javax.sip.header.ims.PPreferredService;
import gov.nist.javax.sip.header.ims.ParameterNamesIms;
import gov.nist.javax.sip.parser.HeaderParser;
import gov.nist.javax.sip.parser.Lexer;
import gov.nist.javax.sip.parser.TokenTypes;
/**
 * 
 * @author aayush.bhatnagar
 * Rancore Technologies Pvt Ltd, Mumbai India.
 * 
 * Parse this: 
 * P-Preferred-Service: urn:urn-7:3gpp-service.exampletelephony.version1
 *
 */
public class PPreferredServiceParser extends HeaderParser implements TokenTypes{

	protected PPreferredServiceParser(Lexer lexer) {
		super(lexer);
	}
	
	public PPreferredServiceParser(String pps)
	{
		super(pps);
	}

	/**
	 * "The URN consists of a hierarchical service identifier or application 
	 * identifier, with a sequence of labels separated by periods.The left-most label is
	 * the most significant one and is called 'top-level service
	 * identifier', while names to the right are called 'sub-services' or
	 * 'sub-applications'.
	 * 
	 * For any given service identifier, labels can be removed right-to-left and
	 * the resulting URN is still valid, referring a more generic
	 * service, with the exception of the top-level service identifier
	 * and possibly the first sub-service or sub-application identifier.
	 * 
	 *  Labels cannot be removed beyond a defined basic service, for
	 *  example, the label w.x may define a service, but the label w may
	 *  only define an assignment authority for assigning subsequent
	 *  values and not define a service in its own right.  In other words,
	 *  if a service identifier 'w.x.y.z' exists, the URNs 'w.x' and
	 *  'w.x.y' are also valid service identifiers, but w may not be a
	 *  valid service identifier if it merely defines who is responsible"
	 * 
	 * TODO: PLEASE VALIDATE MY UNDERSTANDING OF THE ABOVE TEXT :)
	 * @ranga: Please validate my understanding of the above text in the draft :)
	 *         This last para is a little ambiguous.I will only check that atleast 
	 *         1 sub-service or 1 sub-application is present in the URN declaration. 
	 *         If not, I throw an exception. I thought of not throwing an exception
	 *         and returning whatever was encoded..but the resultant encoding wont
	 *         make sense. It would be something like-->
	 *         urn:urn-7:3gpp-service OR urn:urn-7:3gpp-application alone with no sub-services
	 *         or sub-applications. This is bound to cause an error at the recepient later.
	 * 
	 * Sub-service and Application identifiers are not maintained by IANA and 
	 * are organization/application dependent (Section 8.2). So we cannot gurantee what lies
	 * beyond the first sub-service or sub-application identifier. It should be the responsibility
	 * of the application to make sense of the entire URN holistically. We can only check for the 
	 * standardized part as per the ABNF.
	 */
	public SIPHeader parse() throws ParseException {
		if(debug)
			dbg_enter("PPreferredServiceParser.parse");
		try
		{
		
		this.lexer.match(TokenTypes.P_PREFERRED_SERVICE);
		this.lexer.SPorHT();
		this.lexer.match(':');
		this.lexer.SPorHT();
		
		PPreferredService pps = new PPreferredService();
	    String urn = this.lexer.getBuffer();
	    if(urn.contains(ParameterNamesIms.SERVICE_ID)){
	    	
	       if(urn.contains(ParameterNamesIms.SERVICE_ID_LABEL))
	    		   {
	    	        String serviceID = urn.split(ParameterNamesIms.SERVICE_ID_LABEL+".")[1];
	    	        
	    	         if(serviceID.trim().equals(""))
						try {
							throw new InvalidArgumentException("URN should atleast have one sub-service");
						} catch (InvalidArgumentException e) {
							
							e.printStackTrace();
						}
						else
	    	        pps.setSubserviceIdentifiers(serviceID);
	    		   }
	       else if(urn.contains(ParameterNamesIms.APPLICATION_ID_LABEL))
	    	  {
	    	   String appID = urn.split(ParameterNamesIms.APPLICATION_ID_LABEL)[1];
	    	   if(appID.trim().equals(""))
					try {
						throw new InvalidArgumentException("URN should atleast have one sub-application");
					} catch (InvalidArgumentException e) {
						e.printStackTrace();
					}
					else
	    		  pps.setApplicationIdentifiers(appID);
	    	  }
	       else
	       {
	    	   try {
				throw new InvalidArgumentException("URN is not well formed");
				
			} catch (InvalidArgumentException e) {
				e.printStackTrace();
			        }
	              }
	      }
	    
	    	super.parse();
	        return pps;    
		}
		finally{
			if(debug)
				dbg_enter("PPreferredServiceParser.parse");
		}
		
	}
}
